FORT WORTH -- Jolene Price believes that her daughter's death was an accident.

She believed it when she stood by the hospital bed almost 31 years ago, watching as doctors removed the machines that were keeping 15-month-old Heidi Page alive.

And she believes it today, despite learning that authorities have now accused her sister-in-law, Teena Mathis, of killing Heidi.

"I will fight for her [Mathis] because I think it's wrong what they're doing," Price, 48, said Thursday in a telephone interview from Utah. "If they had suspicions, they should have taken care of it years ago, not wait for 31 years or however long it's been and then come back on somebody and do that kind of stuff."

Mathis, a grandmother living in Springtown, surrendered Wednesday to authorities on a murder warrant accusing her of fatally injuring her niece while caring for the girl at her Fort Worth home July 15, 1982, two days before Heidi's death.

"They were outside. Her kids were playing on the swings, then the phone rang and she went in to answer the phone," Price said, relating the account Mathis gave after that terrible day. "My daughter had walked behind the swing set and got hit in the head."

Officers, she said, had observed "numerous bruises" on Heidi's face and body when they were called to the hospital that day.

Mathis told officers that the girl had fallen, which did not explain the injuries, Johnson said.

Although the medical examiner's office ruled Heidi's death a homicide, no arrests were made.

Johnson said the case was recently reviewed by the department's cold case unit and assigned to Detective Kerry Adcock for further investigation.

"The investigation showed that the injuries were inconsistent with a fall," Johnson said.

Johnson said she doesn't know why the case was not pursued in 1982. She said Adcock decided to reinterview those involved and present the case to the district attorney's office, and prosecutors decided to file the charge.

On Thursday, Mathis was charged with murder. She remained in the Mansfield Jail on Thursday afternoon with bail set at $250,000. Her attorney, Jim Lane of Fort Worth, did not immediately return a message seeking comment.

The arrest is the second this week in which a caregiver was charged with murder in the decades-old death of a child. On Tuesday, Patricia Ann Jones was charged with murder in the Sept. 9, 1986, death of her nephew, 19-month-old John P. Jones.

Jones told investigators in 1986 that her nephew was fatally injured when he bounced off the bed and onto the hardwood floor. His death, however, was ruled a homicide.

Though she was arrested a week after the boy's death, Jones was released two days later and was never formally charged. Recently, Fort Worth police reopened the cold case and on Friday -- 26 years later -- Jones was arrested.

Sgt. Rico Lucero, supervisor of the Arlington Police Department's crimes against children unit, said investigation and prosecution of child abuse cases have become more specialized and aggressive. He attributes that change to partnerships built between law enforcement, child advocates, therapists, physicians, Child Protective Services and the district attorney's office, as embodied by Tarrant County's three Alliance For Children centers.

He said that while loved ones might prefer not to pursue prosecution against relatives, the decision is not theirs to make. "It's still a violation of the law," Lucero said. "We still have to seek justice for the person that can't make that decision."

Price said she was a single mother living in Utah when she left Heidi in the care of her brother and his wife in Fort Worth while she prepared to move to Texas.

"They were watching her for me and that's when it happened," she said.

Price said she rushed to Fort Worth after learning that Heidi had been critically injured in what her relatives described as an accident.

"I was there at the hospital when she died," she said.

Price buried her daughter in Utah and abandoned her plans to move. She said that investigators never interviewed her and that, to her knowledge, the case had simply been closed as an accident. She never knew that the Tarrant County medical examiner's office had ruled her daughter's death a homicide, caused by blunt force trauma, she said.

"I believe my sister told me that they were getting interviewed and that's all I ever heard about it," she said. "They never told me anything about what was going on."

Price said she recently got a phone call from a Fort Worth detective.

"They called me and said they had the case still open after all these years," she said. "I asked them to close the case because I felt like it was an accident."

Price said she did not know that her sister-in-law had been arrested until she was contacted by a Star-Telegram reporter. She said she hopes prosecutors will take her opinion into consideration.

"If I thought it was a homicide; it would be different. I don't believe that it was."